Phase shift based precoding method and transceiver for supporting the same.
Abstract
A method of transmitting data using a generalized phase shift based precoding or an extended phase shift precoding scheme in a multiple-antenna system using a plurality of subcarrier and a transceiver for supporting the same are disclosed. A phase shift based precoding matrix may be generalized and determined by a product of a diagonal matrix for phase shift and a unitary matrix for maintaining orthogonality in spatial domain. The diagonal matrix may be extended by a product of a precoding matrix for increasing channel power and the diagonal matrix for phase shift. The design of the transceiver can be simplified or communication efficiency can be improved by generalizing and extending the phase shift based precoding.

Term
0.7 yearsleft in the term
Expires 23 May 2027.
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15 claims: 10 independent, 5 dependent
- 1CLAIMS REIVINDICACIONES 1.- A method for transmitting data using phase shift based precoding in a multiple antenna system using a plurality of 1.- Un método para transmitir datos usando precodificación basada en desplazamiento de fase en un sistema de múltiples antenas usando una pluralidad de 5 subcarriers, the method comprising:5 subportadores, el método comprendiendo: seleccionar una matriz de precodificación de un libro de código como parte de una matriz de precodificación basada en desplazamiento de fase, determinar una matriz diagonal para desplazamiento select a codebook precoding matrix as part of a phase shift based precoding matrix, determine a diagonal matrix for offset 10 phase as a part of the phase shift based precoding matrix;10 de fase como una parte de la matriz de precodificación basada en desplazamiento de fase;determinar una matriz unitaria como parte de la matriz de precodeífricación basada en desplazamiento de fase, determining a unit matrix as part of the phase shift based precoding matrix, 15 multiplicar un producto de la matriz de precodeificación, la matriz diagonal, y la matriz unitaria por un símbolo de una subportadora correspondiente o subbanda para realizar la precodificación. fifteen multiply a product of the precode matrix, the diagonal matrix, and the unit matrix by a symbol of a corresponding subcarrier or subband to perform the precoding.
- 2- El método de conformidad con la reivindicación 2.- The method according to claim 20 1, en donde la matriz unitaria se selecciona mediante operación de módulo de un índice k de la subportadora correspondiente con el tamaño N del libro de código. twenty 1, where the unit matrix is selected by modulating an index k of the corresponding subcarrier with the size N of the codebook.
- 3- El método de conformidad con la reivindicación 3.- The method according to claim 1, en donde el producto de la matriz de precodificación, la matriz diagonal, y la· matriz unitaria se expresa mediante *íjxí) en donde k denota el índice de la subportadora o la sub5 banda, 1, where the product of the precoding matrix, the diagonal matrix, and the · unit matrix is expressed by * íjxí) where k denotes the index of the subcarrier or sub5 band, 9i (i = l, ... R) denotes a phase angle, and R denotes a spatial multiplexing regime. 9i (i=l,...R) denota un ángulo de fase, y R denota un régimen de multiplexión espacial.
- 4- El método de conformidad con la reivíndicaión Four. - The method in accordance with the claim 10 3, where at least one of the precoding matrix, the diagonal matrix, and the unit matrix varies with time. 10 3, en donde cuando menos una de la matriz de precodificación, la matriz diagonal, y la matriz unitaria varía con el tiempo.
- 5- The method according to claim 5. - El método de conformidad con la reivindicación 1, en donde la matriz de precodificación se selecciona sobre la base de información de retroalimentación de un receptor. 1, wherein the precoding matrix is selected based on feedback information from a receiver. 15 15
- 6- El método de conformidad con la reivindicación 6.- The method according to claim 5, en donde la información de retroalimentación contiene un índice de matriz para el libro de código. 5, where the feedback information contains a matrix index for the codebook.
- 7- Dn transceiver to transmit data and perform phase shift based precoding 7. - Dn transceptor para transmitir datos y realizar una precodificación basada en desplazamiento de fase 20 en un sistema de múltiples antes usando una pluralidad de subportadores, el transceptor comprendiendo:twenty in a multiplex system previously using a plurality of subcarriers, the transceiver comprising: a precoding matrix determining module that selects a precoding matrix from a codebook as a part of the phase shift based precoding matrix, determining a diagonal matrix for phase shifting as a part of the based precoding matrix in phase shift, and get a product of the precoding matrix, the diagonal matrix, and the unit matrix for determining the phase shift based precoding matrix;and a precoding module that multiplies the predetermined phase shift based precoding matrix by a symbol of a corresponding subcarrier or subband index. un módulo de determinación de matriz de precodificación que selecciona una matriz de precodificación de un libro de código como una parte de la matriz de precodificación basada en desplazamiento de fase, determinar una matriz diagonal para desplazamiento de fase como una parte de la matriz de precodificación basada en desplazamiento de fase, y obtener un producto de la matriz de precodificación, la matriz diagonal, y la matriz unitaria para determinar la matriz de precodificación basada en desplazamiento de fase;y un módulo de precodificación que multiplica la matriz de precodificación basada en desplazamiento de fase predeterminada por un sí9mbolo de un índice de subportador o sub-banda correspondiente.
- 1010 Claim 7, wherein the precoding matrix is selected on the basis of feedback information from a receiver. 10 reivindicación 7, en donde la matriz de precodificación se selecciona sobre la base· de información de retroalimentación de un receptor.
- 1213. - A method of transmitting data using phase shift based precoding in a multiple antenna system using a plurality of 13. - Un método para transmitir datos usando una precodificación basada en desplazamiento de fase en un sistema de múltiples antenas usando una pluralidad de 20 subportadores, el método comprendiendo:twenty subcarriers, the method comprising: determinar una matriz diagonal para desplazamiento de fase como una parte de la matriz de precodificación basada en desplazamiento de fase;determining a diagonal matrix for phase shift as a part of the phase shift based precoding matrix;determinar una matriz unitaria como una parte de la matriz de precodificación basada en desplazamiento de fase;y determining a unitary matrix as a part of the phase shift based precoding matrix;and 5 multiplying a product of the diagonal matrix and the unit matrix by a symbol of a corresponding subcarrier or subband to perform precoding, where the phase shift based precoding matrix according to the product of the 5 multiplicar un producto de la matriz diagonal y la matriz unitaria por un símbolo de un subportador o sub-banda correspondiente para realizar precodificación, en donde la matriz de precodificación basada en desplazamiento de fase de acuerdo con el producto de la 10 unit matrix and diagonal matrix includes columns that have an identical phase. 10 matriz unitaria y la matriz diagonal incluye columnas que tienen una fase idéntica.
- 1516.- A method to transmit data using a 16.- Un método para transmitir datos usando una 10 phase shift based precoding in a multiple antenna system using a plurality of subcarriers, the method comprising:10 precodificación basada en desplazamiento de fase en un sistema de múltiples antenas que usa una pluralidead de subportadores, el método comprendiendo: determinar primera y segunda matrices diagonales para desplazamiento de fase como una parte de una matriz dew determine first and second diagonal matrices for phase shift as a part of a matrix of w 15 precodificación basada en desplazamiento de fase;fifteen phase shift based precoding;seleccionar una matriz unitaria de un libro de código como parte de la matriz de precodificación basada en desplazamiento de fase;y multiplicar un producto de la primera matriz diagonal, la matriz unitaria, y la segunda matriz diagonal por un símbolo de un subportador correspondiente para realizar la precodificación. selecting a unit matrix from a codebook as part of the phase shift based precoding matrix;and multiplying a product of the first diagonal matrix, the unit matrix, and the second diagonal matrix by a symbol of a corresponding subcarrier to perform the precoding. 5 17.- The method according to claim 16, wherein the product of the first diagonal matrix, the unitary matrix, and the second diagonal matrix is expressed by: 5 17.- El método de conformidad con la reivindicación 16, en donde el producto de la primera matriz diagonal, la matriz unitaria, y la segunda matriz diagonal se expresa mediante: 10 where k denotes the index of the subcarrier or the subband, θί (i = l, ... NJ y 10 en donde k denota el índice del subportadeor o la sub-banda, θί (i=l,... NJ y ΘΊ (j = l, ..., R) denotes a phase angle, and R denotes a regime ΘΊ (j=l,..., R) denota un ángulo de fase, y R denota un régimen 15 de multiplexión espacial. fifteen of spatial multiplexing.
Independent claims10
253 paragraphs in 6 sections, as filed
(54) Title: PRECODIFICATION METHOD BASED ON PHASE DISPLACEMENT AND TRANSCEIVER TO SUPPORT THE SAME.
(54) Title: PHASE SHIFT BASED PRECODING METHOD AND TRANSCEIVER FOR SUPPORTING THE SAME.
(57) Summary
A method of transmitting data using a generalized phase shift based premodification or an extended phase shift premodification scheme in a multiple antenna system using a plurality of subcarriers and a transceiver to support it is described. A phase shift based premodification matrix can be generalized and determined by a product of a diagonal matrix for phase shift and a unitary matrix to maintain orthogonality in the spatial domain. The diagonal matrix can be extended by a product of a premodification matrix to increase channel energy and the diagonal matrix for phase shift. The transceiver design can be simplified or the communication efficiency can be improved by generalizing and extending phase shift based premodification.
(57) Abstract
A method of transmitting data using a generalized phase shift based precoding or an extended phase shift precoding scheme in a multiple-antenna system using a plurality of subcarrier and a transceiver for supporting the same are disclosed. A phase shift based precoding matrix may be generalized and determined by a product of a diagonal matrix for phase shift and a unitary matrix for maintaining orthogonality in spatial domain. The diagonal matrix may be extended by a product of a precoding matrix for increasing channel power and the diagonal matrix for phase shift. The design of the transceiver can be simplified or communication efficiency can be improved by generalizing and extending the phase shift based precoding.
PRECODIFICATION METHOD BASED ON PHASE DISPLACEMENT AND
TRANSCEIVER TO SUPPORT THE SAME
Technical Field
The present invention relates to a generalized phase shift based precoding method or an extended phase shift based precoding method in a multiple antenna system using a plurality of subcarriers and a transceiver to support the same.
Previous bouquet
Recently, as information communication services have become popular, a variety of multimedia services have appeared, and high-quality services have appeared. A requirement for a wireless communication service is increasing rapidly. In order to actively compete with such a trend, a method of increasing communication capacity in a wireless communication environment may include a method of finding a new available frequency band and a method of increasing the efficiency of a restricted resource. As the last method, multiple antenna transmit / receive technologies for mounting a plurality of antennas on a transmitter / receiver and further securing a space to use a resource to obtain a diversity gain or transmit data through the antennas in parallel to increase transmission capacity and attract a lot of attention and are actively developing.
Among the multiple antenna transmit / receive technologies, the general structure of a multiple input multiple output system using an orthogonal frequency division multiplexing (OFDM) will now be described with reference to Figure 1.
In a transmitter, a channel encoder 101 adds redundancy bits to transmission data bits to reduce the influence due to a channel or noise, a tracer apparatus 103 converts data bit information into data symbol information, a converter 105 serial / parallel converts data symbols to parallel data symbols carried on a plurality of subcarriers, and a multi-antenna encoder 107 converts the parallel data symbols into space-time signals, A multi-antenna decoder 109, a parallel / serial converter 111, a destracer 113, and a channel decoder 115 included in a receiver perform reverse functions of multi-antenna encoder 107, serial / parallel converter 105, plotter
103, and channel encoder 101, respectively.
In a multi-antenna OFMD system, a variety of technologies are required to increase increased data transmission reliability. Among them, a scheme to increase the spatial diversity gain includes a space-time code (STC) and a diversity of cyclical delay (CDD) and a scheme to increase the signal-to-noise ratio (SNR) includes a beamformer (BF) and a Precoding. STC and CDD are used to increase the transmission reliability of an open loop system in which a transmitter cannot use feedback information, in a closed loop system in which a transmitter can use feedback information.
Among these schemes, the scheme to increase the gain of spatial diversity and the scheme to increase the
SNR, and more particularly CDD and precoding, will now be described.
In CDD, a system having a plurality of 20 'transmit antennas transmits OFDM signals having different delays or different levels through all the antennas so that a receiver achieves a frequency diversity gain. Figure 2 shows the configuration of a multiple antenna system that uses the
CDD.
OFDM symbols are split and transmitted to the antennas through the serial / parallel converter and the 5 multi-antenna encoder, and added to a cyclic prefix (CP) to prevent interchannel interference to be transmitted to the receiver . Wherein, a data sequence sent to a first antenna is transmitted to the receiver without change, and a data sequence sent to a next antenna is cyclically delayed from the sequence sent to the previous antenna by predetermined bits and then transmitted to the receiver.
Meanwhile, if CDD is implemented in a frequency domain, the cyclic delay can be expressed by a product of phase sequences. That is, as shown in Figure 3, the data sequences in the frequency domain are multiplied by predetermined different phase sequences (phase sequence 1 to phase sequence M) according to the antennas, and are subjected to a Inverse fast Fourier transformation (IFFT), thus being transmitted to the receiver. This is called a phase shift diversity.
If the various phase shift is used, it is possible to change a flat fade channel to a frequency selective channel and obtain a frequency diversity gain through a channel code or obtain a diversity gain from multiple users through frequency selective programming.
Meanwhile, the Precoding includes a codebook-based orecoding that is used when the feedback information is finite in a closed-loop system and a scheme for quantizing and feedback channel information. Among them, in codebook-based precoding, the index of a precoding matrix that is previously known to a transmitter / receiver is transmitted to the transmitter as feedback information to obtain a gain.
SNR.
Figure 4 shows the transmitter / receiver configuration of a multi-antenna system using codebook-based precoding. Transmitter and receiver have Pi to P finite precoding matrices<sub>L</sub>. To receive feedbacks an optimal precoding matrix index I using channel information and the transmitter applies a precoding matrix corresponding to the feedback index to the transmission data Xi to X<sub>M</sub>. Table 1 shows an example of the codebook that is applicable when using 3-bit feedback information in an IEEE.802.16c system that supports a spatial multiplex rate of 2 and has two transmit antennas.
Table 1 [Table 1]
<td>Matrix index (binary}</td><td>Cdumnal</td><td>Column 2</td><td>index of matrix (binary)</td><td>Column1</td><td>Column</td>
<td rowspan="2"> 000</td><td> 1</td><td> 0</td><td rowspan="2">too</td><td> 0.7941</td><td>0X038-JD.Q6S?</td>
<td> 0</td><td> 1</td><td><). 6033 + j0.065?</td><td> -0.7541</td>
<td rowspan="2">IOC</td><td> 0.7940</td><td>-O.5S01 - A1SIS</td><td rowspan="2">i 01</td><td> '732-5?</td><td> 0.6514-)56740</td>
<td> -05801 +)0.1818</td><td> -0.79«</td><td></td><td> 4)3269</td>
<td rowspan="2">autumn</td><td> 0..7940</td><td>0575-jO 5051</td><td rowspan="2">not</td><td> 05112</td><td>0.4754 + j0.71 «</td>
<td> 0.(1575+</td><td> -0.7943</td><td>M754-jO71 »</td><td> 4)3112</td>
<td rowspan="2">on</td><td> 0.7941</td><td>412978 + ÍCL529S</td><td rowspan="2">1Π</td><td> 03289</td><td>-0.8779+ p3431</td>
<td>4Χ297Ϊ ¿05295</td><td> -0.7941</td><td>-G.8779-JGJ451</td><td> 4)3223</td>
Phase shift diversity (PSD) is attracting a lot of attention because a frequency selective diversity gain can be obtained in an open circuit system and a frequency selective programming gain can be obtained in a closed circuit system in addition of the advantages described above. However, since a spatial multiplexing rate is 1, a high data transmission rate cannot be obtained. Furthermore, when the resource allocation is fixed, it is difficult to obtain the gains described above.
Furthermore, since the above-described codebook-based precoding can use a high spatial multiplexing rate while requiring a small amount of feedback information (index information), it is possible to transmit data efficiently. However, since a stable channel for feedback must be ensured, codebook-based precoding is not appropriate for an environment, where channel variation is excessive, and is applicable to only a closed loop system.
Disclosure of Invention
Technical Solution
The present invention is directed to a phase shift based precoding method and a transceiver that substantially avoid one or more problems due to limitations and disadvantages of the foregoing field.
An object of the present invention is to provide a phase shift based precoding method capable of solving the disadvantages of a conventional CDD, a phase shift diversity, and a precoding scheme and variably applying a phase shift based precoding method. phase to generalize or extend the phase shift based precoding matrix.
Additional advantages, objects and features of the invention will be set forth in part in the description which follows and in part will become apparent to those who have ordinary experience in the field after an examination of the following or can be learned from the practice of the invention. The objects and other advantages of the invention can be realized and achieved by means of the structure noted particularly in the written description and claims herein as well as the accompanying drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as is moralized and broadly described herein, a method of transmitting data using phase shift based precoding in a multiple antenna system using a plurality of subcarriers include selecting a precoding matrix from a codebook as a part of the phase shift based precoding matrix; determining a diagonal matrix for phase shift as a part of the phase shift based precoding matrix; determining a unitary matrix as a part of the phase shift based precoding matrix; and multiplying a product of the precoding matrix, the diagonal matrix, and the unit matrix as a symbol for a corresponding subcarrier to perform the precoding.
In another aspect of the present invention, a transceiver for transmitting data and performing phase shift based precoding in a multiple antenna system using a plurality of subcarriers includes a precoding matrix that determines the module by selecting a precoding matrix from a first codebook as part of the phase shift based precoding matrix, determining a diagonal matrix for phase shift as a part of the phase shift based precoding matrix, selecting a unit matrix from a second codebook as a part of the phase shift based precoding matrix, and obtaining a product of the precoding matrix, the diagonal matrix, and the unit matrix to determine the phase shift based precoding matrix; and a precoding module that multiplies the determined phase shift based precoding matrix by a symbol of a corresponding subcarrier.
In another aspect of the present invention, a method of transmitting data using phase shift based precoding in a multiple antenna system using a plurality of subcarriers includes determining a diagonal matrix for phase shift as a part of a matrix of phase shift based precoding; selecting a unit matrix from a codebook as part of the phase shift based precoding matrix; and multiplying a product of the diagonal matrix and the unit matrix by a symbol of a corresponding subcarrier to perform the precoding. The phase shift based precoding matrix according to the product of the unit matrix and the diagonal matrix includes columns that have an identical phase.
In another aspect of the present invention, a method of transmitting data using phase shift based precoding in a multiple antenna system using a plurality of subcarriers includes determining first and second diagonal phase shift matrices as a part of a matrix of phase shift based precoding, select a unit matrix from a codebook as a part of the phase shift based precoding matrix, and multiply a product of the first diagonal matrix, the unit matrix, and the second diagonal matrix by a corresponding subcarrier symbol to perform precoding.
In aspects of the present invention, the unit matrix can be selected by operation of m<sup>z</sup>'odulo (MOD) an index k of the corresponding subcarrier with the size N of the codebook.
In aspects of the present invention, at least one of the precoding matrix, the diagonal matrix (including the first diagonal matrix and the second diagonal matrix), and the unit matrix may be time-variable.
In aspects of the present invention, at least one of the precoding matrix and the unit matrix can be selected based on feedback information from a receiver. Wherein, the feedback information may contain an array index for at least one of the codebook.
It can be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
Brief Description of Drawings
In the accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, they illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings.
Figure 1 is a block diagram showing an orthogonal frequency division multiplexing system 8OFDM) including multiple transmit / receive antennas,
Figure 2 is a block diagram showing a transmitter of a conventional multiple antenna system using a cyclic delay diversity scheme;
Figure 3 is a block diagram showing a transmitter of a conventional multiple antenna system using a phase shift diversity;
Figure 4 is a block diagram showing a conventional multiple antenna system using precoding,
Figure 5 is a block diagram showing the main configuration of a transmitter / receiver for performing phase shift based precoding;
Figure 6 is a graph showing examples of applying phase shift based precoding and phase shift diversity,
Figure 7 is a block diagram showing a single word OFDM (SCW) single transmitter mode using phase shift based precoding in accordance with the mode of the present invention; and
Figure 8 is a block diagram showing an embodiment of a multiple codeword (MCW) OFDM transmitter in accordance with the embodiment of the present invention.
Mode for the Invention
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Whenever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts.
Mode 1
Phase Shift Based Precoding Matrix
Figure 5 is a block diagram of the main configuration of a transceiver for performing phase shift based precoding.
In phase shift based precoding, all currents to be transmitted are through all antennas. And the currents are multiplied by different phase sequences. In general, when the phase sequence is generated using a small cyclic delay, a channel value increases or decreases in accordance with a frequency domain while frequency selectivity occurs on the channel from the point of view of a receiver.
As shown in Figure 5, a transmitter assigns a user terminal at a high frequency to stabilize a channel state in a frequency band that fluctuates depending on a relatively small cyclical delay. Wherein, a phase shift based precoding matrix is used to apply a cyclical delay, which is constantly increasing or decreasing, to each antenna.
The phase shift based precoding matrix P can be expressed by the
Equation 1.
Equation 1
<td></td><td></td><td>k</td><td>k \</td>
<td></td><td></td><td></td><td></td>
<td>pk<sup>1</sup> tyxR "</td><td></td><td> ^2</td><td> · ></td>
<td></td><td></td><td> ^,2</td><td> -</td>
Where, k denotes an index of a subcarrier or an index of a specific frequency band, and
0=1,...
'5 <sup>Nt</sup>, j = l, ... R) denotes a complex weighted value determined by
k. Furthermore, Ni denotes the number of transmit antennas (physical or virtual) and R denotes a spatial multiplexing regime. The complex heavy value can vary depending on the subcarrier index and a specific frequency band that is multiplied by each antenna. The complex heavy value can be determined by at least one of a channel state and the existence of the feedback information.
Meanwhile, the precoding matrix P of the
Preferred Equation 1 is designed by a unitary matrix to reduce loss of channel capacity in a multiple antenna system. In order to test a condition for configuring the unit matrix, the channel capacity of a multi-antenna open circuit system is expressed by Equation 2.
Equation 2 a (H) = where, H denotes a
N<sub>r</sub>xN<sub>t</sub> channel array of multiple antennas and 10 N<sub>r</sub> denotes the number of receiving antennas. Equation 3 is obtained by applying the phase shift based precoding matrix P to Equation 2.
Equation 3
<img file="MX2008014257A_D0001.tif" />
As you can see from Equation 3, in order to avoid loss of channel capacity, PP<sup>H</sup> it must become an identity matrix. Consequently, the phase shift based precoding matrix P must satisfy Equation 4.
Equation 4
In order to allow the phase shift based precoding matrix P to become the unit matrix, two types of conditions, i.e. an energy constraint and an orthogonality constraint, must be satisfied simultaneously. The energy constraint allows the level of each column in the matrix to become 1, and the orthogonality constraint allows the columns in the matrix to have orthogonal characteristics. These are expressed by Equations 5 and 6.
Equation 5<sup>w</sup>or( <sup>+</sup>|<sup>W</sup>2l | <sup>+</sup>' <sup>+</sup> M <sup>_1</sup>'
I<sup>2</sup> . 1..> <sup>,2</sup> + ¡<sup>w</sup>2,2l + = 1,
I | 2 I l2 I | 2 + |<sup>w</sup>2, s | + * • '+ Ρ'λΙ.Λ
Equation 6
<img file="MX2008014257A_D0002.tif" />
<img file="MX2008014257A_D0003.tif" />
<img file="MX2008014257A_D0004.tif" />
Below, an example of the generalized equation of a 2x2 phase shift based precoding matrix is provided and the equations to satisfy the two constraints are obtained. The
Equation 7 shows a generalized equation of a phase shift based precoding matrix when the number of transmit antennas is 2 and a spatial multiplex rate is 2.
Equation 7
<img file="MX2008014257A_D0005.tif" />
where a ^ and bj. (i = 1,2) are real numbers, qi (i = 1, 2, 3,
4) denotes a phase value, and k denotes a specific subcarrier index or subband index of an OFDM signal. In order to implement the precoding matrix with the unit matrix, the energy constraint of Equation 8 and the orthogonality constraint of Equation 9 must be satisfied.
Equation 8 ί<sup>?</sup> T | 4 ~ 3, 1 $ ^^ |<sup>2</sup>'- i
Equation 9
where, the superscript * denotes a complex conjugate number. An example of a phase shift based precoding matrix 2 2 that satisfies Equations 7 to 9 is as follows.
Equation 10
<img file="MX2008014257A_D0006.tif" />
<td rowspan="2">where, q2 Equation 11 orthogonality.</td><td colspan="3">and what<sub>3</sub> have a relationship expressed by the</td>
<td>in accordance</td><td>with the restriction</td><td>of</td>
<td>15 Equation 11</td><td></td><td></td><td></td>
k03 = -k0<sub>2</sub> + π
The precoding matrix can be stored in the transmitter and receiver memory in a codebook form and the codebook can contain a variety of precoding matrices generated using different q<sub>2 </sub>finite. The q<sub>2</sub> it can be adjusted appropriately according to the channel status and the existence of feedback information. If feedback information such as precoding matrix index is used, the q<sub>2</sub> They are small in order to obtain frequency programming gain and, if feedback information is not available, the q<sub>2</sub> they are large, thereby obtaining a high frequency diversity gain.
Meanwhile, a frequency diversity gain or a frequency schedule gain can be obtained in accordance with a delay sample value applied to phase shift based precoding. Figure 6 is a graph showing examples of applying phase shift based precoding and phase shift diversity in accordance with the delay sample value.
As shown in Figure 6, since a frequency selective period is short if a large delay sample value (or a large cyclical delay) is used, the frequency selectivity increases and the channel code exploits a diversity gain frequency easily.
This is preferably used in an open-circuit system where the channel value varies significantly over time and the reliability of the feedback information deteriorates.
If a small delay sample value is used, a portion in which the channel value increases and a portion in which the channel value decreases are included in a frequency selective channel changed from a flat fade channel. Consequently, the channel value of any subband (subcarrier region) of the OFDM symbol increases and the channel value of the other subcarrier region thereof decreases.
In the orthogonal frequency division multiple access system (OFDMA) that can support a plurality of users, when a signal is transmitted to each user through the frequency band in which the channel value increases, an SNR can increase . Since the degree of allocation of the frequency band, in which the channel value increases, can vary for each user, the system obtains a programming gain from multiple users.
The sample delay (or cyclic delay) value for phase shift based precoding may be a value that is pre-determined at the transmitter / receiver or a receiver feedback information. The spatial multiplexing rate R may be a value that is pre-determined at the transmitter / receiver. Alternatively, the receiver may periodically check the channel status, calculate the spatial multiplexing rate, and feed back the spatial multiplexing rate to the transmitter, or the transmitter may calculate and change the spatial multiplexing rate using the channel information from the receiver.
Mode 2
Generalized Phase Displacement Diversity Matrix
The phase shift based precoding matrix described above can be expressed by Equation 12 with respect to a system in which the number (physical or virtual) of antennas N<sub>t</sub> (N<sub>t</sub> is a positive number of 2 or more) and the spatial multiplexing rate is
R (R is a positive number of 1 or more). Since this equation is obtained by generalizing the conventional phase shift diversity. The multiple antenna scheme expressed by Equation 12 is also called a generalized phase shift diversity (GPSD).
Equation 12 gpsd ^.<sub>xr</sub> =
<td> 1.1</td><td> ^2 -</td><td></td><td></td><td>'V</td><td> 0</td><td> ... 0 '</td>
<td> <1</td><td>χ<sub>2</sub> -·</td><td>Ar</td><td></td><td> 0</td><td></td><td> ... 0</td>
<td> •</td><td> • ’</td><td> •</td><td></td><td></td><td></td><td> '·. 0</td>
<td>Λ<sup>1</sup></td><td>-mA · * · ^, 2</td><td><sup>w</sup>rij</td><td></td><td>L o</td><td> 0</td><td> 0 <sub>></sub></td>
where
GPSD ^<sub>R</sub> denotes a GPSD matrix of k<sup>th</sup> subband or subcarrier of a MIMO-OFDM signal having a spatial multiplexing regime R and transmitting (physical or virtual) antennas N<sub>t</sub> and denotes a satisfying unitary matrix that is used to minimize interference between the subcarrier symbol corresponding to each antenna. In particular, in order to maintain the unit matrix characteristics of a diagonal phase shift matrix, it is preferable that »
satisfy the condition of the unit matrix. In the equation
12, a relationship between a phase angle q¿ (i = 1, - N¿) of a frequency domain and a delay time ti (i = l, ... Ni) of a time domain is expressed by the
Equation 13.
Equation 13
<img file="MX2008014257A_D0007.tif" />
T:
where, N<sub>m</sub> denotes the number of signal subcarriers
OFDM.
As a modified example of Equation 12, a GPSD matrix can be obtained as follows.
Equation 14
<td></td><td>F "L, l</td><td></td><td> ·</td><td></td><td></td><td> 0</td><td>... or </td>
<td></td><td></td><td> <2</td><td>- Xj¡</td><td>"('you</td><td> 0</td><td>and**</td><td> ··· 0</td>
<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> '·. 0</td>
<td></td><td></td><td></td><td></td><td></td><td> < 0</td><td> 0</td><td> 0</td>
When the GPSD matrix of Equation 14 is obtained, the data stream symbols (or subcarriers of
OFDM) move through an identical phase and in this way the arrangement of the matrix is facilitated. That is, while the GPSD matrix of Equation 12 has rows that have identical phase, the GPSD matrix of Equation 14 has columns that have an identical phase. Subcarrier symbols move through the identical phase. When Equation 14 is extended, a GPSD matrix can be obtained in the following way expressed by Equation 15.
Equation 15 w:
1,2
Λ
2,2
w.
í e<sup>yes</sup>
... oo
oe<sup>10</sup>”* • e, k
- or
- o '·. or
In accordance with Equation 15, since the rows and columns of the GPSD matrix have independent phases, a greater variety of frequency diversity gains can be obtained.
As an example of Equations 12, 14, and 15, the GPSD matrix of a system that uses 1-bit codebook and that has two transmit antennas is expressed by the
Equation 16.
Equation 16
GPSD ^<sub>2</sub>= ^ J<sub>to</sub>and <sub>to</sub><sup>2</sup> + /? = l
In Equation 16, if a is determined, b is easily determined. Consequently, the a can be adjusted to have two values and the information about the a can be transmitted as a feedback codebook index. For example, during the mutual agreement between the transmitter and receiver, a is set to 0.2 if the feedback rate is 0 and is set to 0.8 if the feedback rate is 1.
In Equations 12, 14 and 15, as an example of the unit matrix
A, * R a default precoding matrix to obtain an SNR gain can be used. As such a precoding matrix, a Walsh Hadarmard matrix or a DFT matrix can be used. Among them, when using the Walsh matrix
Hadarmad, an example of the GPSD matrix from Equation 12 is expressed by Equation 17.
Equation 17 € 7ΡΜχ4 =
OO e '
OR
OR
OR
W f 1 1 1
U • 1
1
1/
Equation 17 is obtained based on the system that has the spatial multiplexing regime of 4 and four transmission antennas. By appropriately reconfiguring the unit matrix, a specific transmission antenna can be selected or the spatial multiplexing rate can be tuned.
Meanwhile, the unit matrix
An, * R from Equations 12, 14, and 15 can be included in the transmitter and receiver in codebook form. In this case, the transmitter receives the index information from the transmitted codebook from the receiver, selects the unit matrix of the codebook index included therein, and configures a phase shift based precoding matrix using one of the Equations 12, 14 and
15.
Examples of GPSD matrices using 2x2 and 4x4 Walsh codes as the unit matrix
U from Equation 12, 14 and 15 are as follows:
Table 2
<td colspan="2"></td>
<td>Regime 1</td><td>Regime 2</td>
<td>. ΐΓ 1 W *</td><td>Φ <sup>1</sup>1</td>
Table 3
<td colspan="9">4Tx</td>
<td colspan="3">Regime 1</td><td colspan="3">Regime 2</td><td></td><td>Regimen 4</td><td></td>
<td> 1 2</td><td>'1' g * and/*</td><td></td><td> 1 .2</td><td>'eleven fy®</td><td></td><td> 1 2</td><td>'1 1 1 Γ é * -e * and f y * yt</td><td></td>
Mode 3
Time-Variable Phase Displacement Diversity
Generalized.
In the GPSD matrices of Equations 12, 14 and 15, the phase angle of the diagonal matrix and / or the unit matrix U may vary with time. For example, a time-variable GPSD from Equation 12 can be expressed as ς
<td colspan="5">using Equation 18</td>
<td>Equation 18</td><td></td><td> 0 -</td><td>Q </td><td></td>
<td></td><td> 0</td><td></td><td> 0</td><td></td>
<td>í, X <..<sub>s</sub>(z)</td><td></td><td> * .»</td><td>-w 0</td><td></td>
<td></td><td> , 0</td><td> 0 0</td><td> /</td><td></td>
<td>where,</td><td></td><td></td><td></td><td></td>
<td>GPSD ^<sub>R</sub>(t)</td><td></td><td></td><td></td><td></td>
<td colspan="2">denotes a GPSD matrix</td><td>of a</td><td></td><td></td>
k<sup>th</sup>
Subcarrier or subband of a MIMO-OFDM that has a spatial multiplexing regime of R and N<sub>t</sub> transmit antennas 10 (physical or virtual) at a specific time and (0 denotes a unitary matrix (fourth matrix) to satisfy that is used to minimize the interference between .carrier symbol corresponding to each antenna. In particular, in order to maintain the unit matrix characteristics of a diagonal matrix (third matrix) 'for phase shift, it is preferable that it satisfy the condition of the unit matrix.
18, a relation between a phase angle θϊ (i = 1, ... N<sub>t</sub>) and a delay time τι (i = 1, ... N<sub>t</sub>) is expressed by Equation 19
Equation 19
<img file="MX2008014257A_D0008.tif" />
where Nm denotes the number of signal subcarriers
OFDM.
As you can see from Equations 18 and 19, the time lag sample value and the unit matrix may vary over time. The time unit may be an OFDN symbol unit or a predetermined time unit.
Examples of GPSD matrices that use codes
Walsh 2x2 and 4x4 as the uni8tary matrix to obtain the GPSD variables in time are shown in Tables 4 and 5.
Table 4
<td colspan="2">, 2Tx</td>
<td>Regime 1</td><td>Regime 2</td>
<td>i-1 .O <</td><td>Γ1 i 1</td>
Table 5
<td colspan="8">4Tx</td>
<td colspan="3">Regime í</td><td colspan="3">Regime 2</td><td colspan="2">Regimen 4</td>
<td></td><td> 1</td><td></td><td></td><td> 1 1</td><td></td><td></td><td> 1 1 1 1 ]</td>
<td></td><td>g / SW</td><td></td><td></td><td></td><td></td><td></td><td></td>
<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>giW ¿W</td>
<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>
Even though the time-variable GPSD matrix of the
Equation 12 is described in Mode 3, the diagonal matrix and the unit matrix of Equations 14 and 15 can be used. Consequently, even when Equation 12 is described in the following modalities, it is evident to those skilled in the art that Equations 14 and 15 can be similarly extended and used
Mode 4
Phase Displacement Diversity Expansion
Generalized
In Mode 2, an extended GPSD matrix can be configured by adding the corresponding third matrix 5 to the precoding matrix to the GPSD matrix composed of the diagonal matrix and the unit matrix. This is expressed by Equation 20.
Equation 20
GPSJD *
The extended GPSDE matrix is characterized in that an Nt R recoding matrix P is added in front of the diagonal matrix of Equation 12 · and the size of the diagonal matrix is used in the virtual antenna domain (Nt = R), thus changed way to RxR. The added precoding matrix
P <sup>1</sup> N, xR can be different from a specific frequency band or a specific subcarrier symbol and preferably can be fitted to a unit matrix. It is possible to obtain an optimized SNR gain by adding the precoding matrix,
Q if feedback information is available.
It is preferable that the transmitter and receiver include a codebook containing a plurality of precoding P matrices.
Meanwhile, in the extended GPSD matrix, at least one of the precoding matrix P, the phase angle q of the diagonal matrix, and the unit U matrix may vary over time. When the index of a subsequent precoding matrix P is transmitted in the predetermined time unit or the predetermined subcarrier unit, a specific precoding matrix P corresponding to the index can be selected in a predetermined codebook.
The GPSD matrix extended in accordance with the present modality can be expressed by Equation 21.
Equation 21
As an example of the extended GPSD matrix, a matrix of a multiple antenna system that has two transmission antennas and a matrix of a multiple antenna system that has four transmission antennas are expressed by Equations 22 and 23. A DFT matrix is you can use as the unitary U matrix, but the pervasive invention is not limited to this. Any array can be used as long as the array satisfies the unit condition such as the Walsh Hadarmard code.
Equation 22
GPS ^ <sub>2</sub> (t) = (P<sub>3 x 2</sub> (í)) (J / [t)<sub>k</sub> pFT<sub>2 x 2</sub>)
Equation 23
or
C e ^<sup>íiÍ5</sup>
V oo
Mode 5
Transmitter / Receiver to Perform Phase shift based precoding.
In general, a communication system includes a transmitter and a receiver. The transmitter and receiver can be a transceiver that can perform a transmit function and a receive function. In order to clarify the description of the feedback, a device for transmitting data is called a transmitter and a device for feeding data back to the transmitter is called a receiver.
In a downlink, the transmitter can be a part of a base station and the receiver can be a part of a terminal. In an uplink, the transmitter can be a part of a terminal and the receiver can be a part of a base station. The base station can include a plurality of receivers and a plurality of transmitters, and the terminal can include a plurality of receivers and a plurality of transmitters. In general, since the receiver setup has the inverse functions of the transmitter functions, only the transmitter will be described in detail.
Figure 7 is a block diagram showing one embodiment of a single codeword OFDM (SCW) transmitter using phase shift based precoding in accordance with the embodiment of the present invention, and Figure 8 is a diagram block showing an embodiment of a multiple codeword (MCW) OFDM transmitter in accordance with the embodiment of the present invention.
Since configurations including 510 and 610 channel encoders, 520 and 620 interleavers, the 8lFFTs) and
6650, and 560 and 660 analog converters are similar to those in Figure 1, the description thereof will be omitted. Only the 540 and 640 predecoder will be described in detail.
The 540 and 640 predecoder includes 541 modules and
641 for determining the precoding matrix and modules *
542 and 642 precoding.
The precoding matrix determination modules 541 and 641 determine phase shift based precoding matrices by one of Equations 12, 14, 15, 20 and 21. Since the precoding matrix determination method is described in detail in through the
Modalities 2 to 4, the description of the same will be omitted. The phase shift based precoding matrix determined by one of Equations 12, 14, 15, 20, and 21 can be changed to the precoding matrix to eliminate interference between subcarriers, the phase angle of the diagonal matrix, and / or the unitary matrix of conformity with time, as expressed by Equation 18.
The precoding matrix determining modules 541 and 641 can select at least one of the precoding matrix and the unit matrix based on the feedback information from the receiver. Where it is preferable that the feedback information contains an array index for a predetermined codebook.
Precoding modules 542 and 642 multiply the phase shift based precoding matrix determined by an OFDM symbol from a corresponding subcarrier to perform precoding.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without abandoning the spirit or scope of the inventions. Thus, the present invention is intended to cover modifications and variations of this invention as long as they fall within the scope of the appended claims and their equivalents.
Industrial Applicability
In accordance with the embodiment of the present invention, it is possible to implement efficient communication using phase shift based precoding that overcomes the disadvantages of conventional cyclic delay diversity, phase shift diversity, and precoding schemes and to further improve the communication efficiency or simplify transmitter / receiver design by generalizing or extending phase shift based precoding.
Contents6
14 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11 Sheet 12 Sheet 13 Sheet 14
20 priority claims, no other members on record
Priority claims20
| Document | Office | Kind | Date |
|---|---|---|---|
| 80334006 | United States of America | P | |
| 80334006 | United States of America | P | |
| 88989107 | United States of America | P | |
| 88989107 | United States of America | P | |
| 89466507 | United States of America | P | |
| 89466507 | United States of America | P | |
| 20070037008 | Republic of Korea | A | |
| 20070037008 | Republic of Korea | A | |
| 2007002500 | Republic of Korea | W | |
| 2007002500 | Republic of Korea | W | |
| 1020070037008 | – | – | – |
| 60803340 | – | – | – |
| 60889891 | – | – | – |
| 60894665 | – | – | – |
| KR0702500 | – | – | – |
| KR20070037008 | – | – | – |
| US20060803340P | – | – | – |
| US20070889891P | – | – | – |
| US20070894665P | – | – | – |
| WO2007KR02500 | – | – | – |
1 legal event, as the office reported them to INPADOC
Events
| Event | Code | |
|---|---|---|
| Grant or registrationFG | FG |
Numbers
- Publication, DOCDB
- 2008014257
- Publication, EPODOC
- MX2008014257
- Application
- 2008014257
- Application, DOCDB
- 2008014257
- Application, EPODOC
- MX20080014257
Titles2
- English
- PHASE SHIFT BASED PRECODING METHOD AND TRANSCEIVER FOR SUPPORTING THE SAME.
- Spanish
- METODO DE PRECODIFICACION BASADO EN DESPLAZAMIENTO DE FASE Y TRANSCEPTOR PARA SOPORTAR EL MISMO.
Classification
- CPC, 11
- H04L1/02
- H04B7/0456
- H04B7/0671
- H04B7/0682
- H04L25/03343
- H04L27/2626
- H04L25/03898
- H04B7/0639
- H04B7/0465
- H04L27/2628
- H04B5/26
- IPC, 7
- H04N7 06
- H04B7 02
- H04B7 04
- H04J11 00
- H04J99 00
- H04L1 00
- H04L1 06